What you do last weekend? [ ]
A. does
B. do
C. did
答案：C
确定牙髓炎的患牙简便而可靠的方法是
A．温度测验
B．电活力测验
C．酸、甜测验
D．探查
E．叩诊
在自动喷水灭火系统中，公称直径大于200mm的雨淋报警阀，应在（）之内启动。
A.40s
B.60s
C.60s
D.100s
